This invention relates generally to injection molding and more particularly to a heated nozzle having a nozzle seal provided by two removable inserts.
It is well known to seat a heated nozzle in a cooled mold with an insulative air space between them and to bridge the insulative air space by a nozzle seal removably mounted in the front end of the nozzle. An example where the nozzle seal has a prying flange for removal is shown in U.S. Pat. No. 5,028,227 to Gellert et al. which issued Jul. 2, 1991. Another example where the nozzle seal, which is also a gate insert, is screwed into the front end of the nozzle is seen in U.S. Pat. No. 4,793,795 to Schmidt et al. which issued Dec. 27, 1988. The applicant's U.S. Pat. No. 5,282,735 which issued Feb. 1, 1994 shows that it is also known to use a nozzle seal to securely retain a torpedo in place in a seat in the front end of a nozzle. The applicant's U.S. Pat. No. 5,284,436 which issued Feb. 8, 1994 shows a torpedo which also forms the nozzle seal with a separate gate insert seated in the mold. The applicant's U.S. Pat. No. 5,299,928 which issued Apr. 5, 1994 shows a two-piece nozzle seal with the inner piece being secured in place by a threaded outer piece.
While some of these previous arrangements deal with the removal of one piece, there is no provision for convenient removal of a nozzle seal having two pieces. Convenient removal for cleaning and for replacement due to wear and corrosion or to change the gate size in the case of a gate insert is very important. It is time consuming and costly if sticking occurs and disassembly of the mold is required to remove the nozzle seal.